From eb3ee278bcf97fff45e19e3ad7f70bc3a318208a Mon Sep 17 00:00:00 2001
From: rwatson <rwatson@FreeBSD.org>
Date: Thu, 19 Aug 2004 01:13:10 +0000
Subject: [PATCH] Push down pcbinfo and inpcb locking from udp_send() into
 udp_output(). This provides greater context for the locking and allows us to
 avoid locking the pcbinfo structure if not binding operations will take place
 (i.e., already bound, connected, and no expliti sendto() address).

---
 sys/netinet/udp_usrreq.c | 60 +++++++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/sys/netinet/udp_usrreq.c b/sys/netinet/udp_usrreq.c
index fec2b1ca2148..5f1a1bb24aac 100644
--- a/sys/netinet/udp_usrreq.c
+++ b/sys/netinet/udp_usrreq.c
@@ -729,17 +729,19 @@ udp_output(inp, m, addr, control, td)
 	int error = 0;
 	int ipflags;
 	u_short fport, lport;
+	int unlock_udbinfo;
 
-	INP_LOCK_ASSERT(inp);
-#ifdef MAC
-	mac_create_mbuf_from_inpcb(inp, m);
-#endif
-
+	/*
+	 * udp_output() may need to temporarily bind or connect the current
+	 * inpcb.  As such, we don't know up front what inpcb locks we will
+	 * need.  Do any work to decide what is needed up front before
+	 * acquiring locks.
+	 */
 	if (len + sizeof(struct udpiphdr) > IP_MAXPACKET) {
-		error = EMSGSIZE;
 		if (control)
 			m_freem(control);
-		goto release;
+		m_freem(m);
+		return EMSGSIZE;
 	}
 
 	src.sin_addr.s_addr = INADDR_ANY;
@@ -749,9 +751,9 @@ udp_output(inp, m, addr, control, td)
 		 * is stored in a single mbuf.
 		 */
 		if (control->m_next) {
-			error = EINVAL;
 			m_freem(control);
-			goto release;
+			m_freem(m);
+			return EINVAL;
 		}
 		for (; control->m_len > 0;
 		    control->m_data += CMSG_ALIGN(cm->cmsg_len),
@@ -787,8 +789,23 @@ udp_output(inp, m, addr, control, td)
 		}
 		m_freem(control);
 	}
-	if (error)
-		goto release;
+	if (error) {
+		m_freem(m);
+		return error;
+	}
+
+	if (src.sin_addr.s_addr != INADDR_ANY ||
+	    addr != NULL) {
+		INP_INFO_WLOCK(&udbinfo);
+		unlock_udbinfo = 1;
+	} else
+		unlock_udbinfo = 0;
+	INP_LOCK(inp);
+
+#ifdef MAC
+	mac_create_mbuf_from_inpcb(inp, m);
+#endif
+
 	laddr = inp->inp_laddr;
 	lport = inp->inp_lport;
 	if (src.sin_addr.s_addr != INADDR_ANY) {
@@ -879,11 +896,17 @@ udp_output(inp, m, addr, control, td)
 	((struct ip *)ui)->ip_tos = inp->inp_ip_tos;	/* XXX */
 	udpstat.udps_opackets++;
 
+	if (unlock_udbinfo)
+		INP_INFO_WUNLOCK(&udbinfo);
 	error = ip_output(m, inp->inp_options, NULL, ipflags,
 	    inp->inp_moptions, inp);
+	INP_UNLOCK(inp);
 	return (error);
 
 release:
+	INP_UNLOCK(inp);
+	if (unlock_udbinfo)
+		INP_INFO_WUNLOCK(&udbinfo);
 	m_freem(m);
 	return (error);
 }
@@ -1065,22 +1088,9 @@ udp_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
 	    struct mbuf *control, struct thread *td)
 {
 	struct inpcb *inp;
-	int ret;
 
-	INP_INFO_WLOCK(&udbinfo);
 	inp = sotoinpcb(so);
-	if (inp == 0) {
-		INP_INFO_WUNLOCK(&udbinfo);
-		m_freem(m);
-		if (control != NULL)
-			m_freem(control);
-		return EINVAL;
-	}
-	INP_LOCK(inp);
-	ret = udp_output(inp, m, addr, control, td);
-	INP_UNLOCK(inp);
-	INP_INFO_WUNLOCK(&udbinfo);
-	return ret;
+	return udp_output(inp, m, addr, control, td);
 }
 
 int